According to United States Health and Human Services (USHHS) 2002 Report on Mental Health in the United States, approximately 3.7% of children 5-17 years old will be diagnosed with depression in a given year. That means approximately 2.2 million annually for a child/adolescent market of US$440 million if averaging 1 scan per patient. According to the National Institute for Mental Health (NIMH), every year 9.5% of the population suffers one or more depressive disorders, with women experiencing depression about twice as often as men. In the United States, this means about 28.1 million annually for a general population market worth about US$5.62 billion if averaging 1 scan per patient. While diagnosis may only require one scan, tracking of treatment may require multiple scans.
Quantitative electroencephalography (qEEG) has been utilized by some healthcare professionals to analyze and diagnose certain psychopathological conditions. For instance, literature has reported nearly 100 studies which have examined qEEG in association with emotions and related psychopathology (See Allen & Kline, 2004; Coan & Allen, 2004). In some of these studies, asymmetry between left and right frontal qEEG measurements has been observed to be associated with individuals either demonstrating or being at risk for depressive psychopathology. One analysis of qEEG measurements for asymmetry can be performed utilizing a Fast Fourier Transform (FFT) that can provide averaged results for all epochs accepted after artifacting. At least two studies have observed greater statistical differences between experimental groups by using an analysis that includes FFT of each individual epoch and then determination of a percentage time with left or right favored asymmetry (See Baehr, Rosenfeld, Baehr, & Earnest, 1998; Baehr, Rosenfeld, Miller, & Baehr, 2004).
Quantitative electroencephalography (qEEG) has also been used by other healthcare professionals or personnel for other types of monitoring, such as monitoring the effects of anesthesia on a patient. For example, analysis of qEEG measurements using discriminant analysis can provide a discriminant variable called “cordance.” This type of analysis can also be used for investigating brain lesions and characterizing patients with dementia.
Frontal alpha qEEG asymmetry has been commonly used by healthcare professionals and researchers to investigate depressive disorders. Conventional techniques utilizing calculation of asymmetry, such as simple arithmetic difference between the power values of the two hemispheres, to identify depression have been used by healthcare professionals. One technique, such as neurofeedback, biofeedback or neurotherapy, uses qEEG asymmetry as a marker variable to treat depression. This technique uses simple subtraction of left and right hemisphere power variables. Other similar techniques examine an arithmetic difference between power values of the frontal regions of the left and right hemispheres determined using an FFT of all included epochs averaged in combined sets. There can be substantial variability in the power at the frontal sites of each hemisphere. With prior techniques, valuable information from the variability can be lost in the averaging process, and valuable information from the averaged values can be diminished when not accounting for the variability. Meta-analysis of various literature using such conventional techniques can produce an effect size of approximately 0.6, which estimates a classification accuracy of about 60%. That is, identification and diagnosis of depression using such conventional techniques can be approximately 60% accurate.
One conventional technique uses a discriminant analysis and a cluster analysis to diagnose depression. This technique can require discriminant analysis of specific qEEG variables including those of absolute power, relative power, coherence, and asymmetry. However, this technique can also utilize the qEEG variables in the manner typical for the field as described above, which can lose valuable information from the variability.
Single recordings of qEEG measurements can be utilized to analyze or investigate asymmetry. Some studies have utilized a repeated measures design coupled with a relatively simple method for isolating relatively stable qEEG components. This static-type method involves a basic averaging technique with the repeated measures, and can lead to improved precision in the investigation and analysis of asymmetrical qEEG measurements and results. See (Davidson, 1998).
One mathematical technique can separate qEEG measurements into respective static components and dynamic components. Prior applications of this technique have been limited to studies of qEEG and genetics, which demonstrated the effectiveness of this type of analysis in determining the stable, genetic components of qEEG. When using this technique in studies of dizygotic and monozygotic twins as well as immediate family members and the general population, genetic similarity between individuals has been associated with the spectral pattern similarity of the stable components of the qEEG data (Stassen, Lykken, Propping, & Bomben, 1988).
Therefore, a need exists for systems and methods for analyzing and assessing depression in an individual using electroencephalographic measurements. Another need exists for systems and methods for analyzing and assessing mood disorders in an individual using electroencephalographic measurements.
Yet another need exists for systems and method for analyzing and assessing bipolar disorder in an individual using electroencephalographic measurements.
Yet another need exists for systems and method for analyzing and assessing a disorder with at least one genetic-related component in an individual using electroencephalographic measurements.